/*
 * Copyright (C) 2015 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.javapoet;

import static java.lang.Character.isISOControl;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.lang.model.element.Modifier;

/**
 * Like Guava, but worse and standalone. This makes it easier to mix JavaPoet
 * with libraries that bring their own version of Guava.
 */
final class Util {
	private Util() {
	}

	static <K, V> Map<K, List<V>> immutableMultimap(Map<K, List<V>> multimap) {
		LinkedHashMap<K, List<V>> result = new LinkedHashMap<>();
		for (Map.Entry<K, List<V>> entry : multimap.entrySet()) {
			if (entry.getValue().isEmpty())
				continue;
			result.put(entry.getKey(), immutableList(entry.getValue()));
		}
		return Collections.unmodifiableMap(result);
	}

	static <K, V> Map<K, V> immutableMap(Map<K, V> map) {
		return Collections.unmodifiableMap(new LinkedHashMap<>(map));
	}

	static void checkArgument(boolean condition, String format, Object... args) {
		if (!condition)
			throw new IllegalArgumentException(String.format(format, args));
	}

	static <T> T checkNotNull(T reference, String format, Object... args) {
		if (reference == null)
			throw new NullPointerException(String.format(format, args));
		return reference;
	}

	static void checkState(boolean condition, String format, Object... args) {
		if (!condition)
			throw new IllegalStateException(String.format(format, args));
	}

	static <T> List<T> immutableList(Collection<T> collection) {
		return Collections.unmodifiableList(new ArrayList<>(collection));
	}

	static <T> Set<T> immutableSet(Collection<T> set) {
		return Collections.unmodifiableSet(new LinkedHashSet<>(set));
	}

	static <T> Set<T> union(Set<T> a, Set<T> b) {
		Set<T> result = new LinkedHashSet<>();
		result.addAll(a);
		result.addAll(b);
		return result;
	}

	static void requireExactlyOneOf(Set<Modifier> modifiers, Modifier... mutuallyExclusive) {
		int count = 0;
		for (Modifier modifier : mutuallyExclusive) {
			if (modifiers.contains(modifier))
				count++;
		}
		checkArgument(count == 1, "modifiers %s must contain one of %s", modifiers, Arrays.toString(mutuallyExclusive));
	}

	static String characterLiteralWithoutSingleQuotes(char c) {
		// see https://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6
		switch (c) {
		case '\b':
			return "\\b"; /* \u0008: backspace (BS) */
		case '\t':
			return "\\t"; /* \u0009: horizontal tab (HT) */
		case '\n':
			return "\\n"; /* \u000a: linefeed (LF) */
		case '\f':
			return "\\f"; /* \u000c: form feed (FF) */
		case '\r':
			return "\\r"; /* \u000d: carriage return (CR) */
		case '\"':
			return "\""; /* \u0022: double quote (") */
		case '\'':
			return "\\'"; /* \u0027: single quote (') */
		case '\\':
			return "\\\\"; /* \u005c: backslash (\) */
		default:
			return isISOControl(c) ? String.format("\\u%04x", (int) c) : Character.toString(c);
		}
	}

	/**
	 * Returns the string literal representing {@code value}, including wrapping
	 * double quotes.
	 */
	static String stringLiteralWithDoubleQuotes(String value, String indent) {
		StringBuilder result = new StringBuilder(value.length() + 2);
		result.append('"');
		for (int i = 0; i < value.length(); i++) {
			char c = value.charAt(i);
			// trivial case: single quote must not be escaped
			if (c == '\'') {
				result.append("'");
				continue;
			}
			// trivial case: double quotes must be escaped
			if (c == '\"') {
				result.append("\\\"");
				continue;
			}
			// default case: just let character literal do its work
			result.append(characterLiteralWithoutSingleQuotes(c));
			// need to append indent after linefeed?
			if (c == '\n' && i + 1 < value.length()) {
				result.append("\"\n").append(indent).append(indent).append("+ \"");
			}
		}
		result.append('"');
		return result.toString();
	}
}
